Question

  aJsonObject* sBoard = aJson.createObject();
  aJsonObject* sensorType = aJson.createObject();

  aJsonObject* sBoard = aJson.createObject();
  aJsonObject* sensorType = aJson.createObject();

  aJson.addItemToObject(sBoard, "name", aJson.createItem("SensorBoardOne"));
  aJson.addItemToObject(sBoard, "Sensor", sensorType);

  aJson.addNumberToObject(sensorType, "ph", 5.33);
  aJson.addNumberToObject(sensorType, "ec", 880);
  aJson.addNumberToObject(sensorType, "temp", 74.68);

  aJsonObject* ph = aJson.getObjectItem(sensorType, "ph");

  Serial.println(ph->valuefloat);

Serial.println(ph->valuefloat);返回0.00。我之前从未处理过C结构，也不确定我是否正确设置了语法。我的json结构似乎相当直接;但是，我不确定我是否正在访问ph float值的正确creatObject（）。我该怎么做才能获得适当的ph值？

有关aJSON库的更多信息，请访问：http://interactive-matter.eu/blog/2010/08/14/ajson-handle-json-with-arduino/

编辑新代码：

  aJsonObject* sBoard = aJson.createObject();

  aJson.addItemToObject(sBoard, "name", aJson.createItem("SensorBoardOne"));

  aJson.addNumberToObject(sBoard, "ph", 5.33);
  aJson.addNumberToObject(sBoard, "ec", 880);
  aJson.addNumberToObject(sBoard, "temp", 74.68);

  aJsonObject* phValue = aJson.getObjectItem(sBoard, "ph");
  char* string = aJson.print(sBoard);
    if (string != NULL) {
      Serial.println(string); //prints out: {"name":"SensorBoardOne","ph":5.33000,"ec":880,"temp":74.68000}

    }

  Serial.println(phValue->valuefloat);

我最终将json结构更改为更简单的结构。我觉得由于arduino的ram短缺，不需要另一个子结构。缩短json结构后，我能够成功获得ph值的值。我仍然有兴趣找出先前的问题以供将来参考。

Answer 1

我刚试过你的代码，发现你已经在代码片段的开头两次声明了sBoard和sensorType。

我删除了它，我得到了正确的回复＆＃34; 5.33＆＃34;。这是我在编辑后使用的代码。

  aJsonObject* sBoard = aJson.createObject();
  aJsonObject* sensorType = aJson.createObject();

  aJson.addItemToObject(sBoard, "name", aJson.createItem("SensorBoardOne"));
  aJson.addItemToObject(sBoard, "Sensor", sensorType);

  aJson.addNumberToObject(sensorType, "ph", 5.33);
  aJson.addNumberToObject(sensorType, "ec", 880);
  aJson.addNumberToObject(sensorType, "temp", 74.68);

  aJsonObject* ph = aJson.getObjectItem(sensorType, "ph");

  Serial.println(ph->valuefloat);

arduino aJSON库valuefloat始终返回0.00

1 个答案: